1. Field of the Invention
The present invention relates to an information setting device for a camera, in which control information such as shutter speed or aperture value etc. is set in accordance with the operation of an information setting operation member such as an electronic dial or the like.
2. Description of the Related Art
An information setting device for a camera is per se known, which is provided with an information setting operation member such as a rotatable electronic dial which generates a pulse signal according to the amount by which it is rotated (hereinafter simply referred to as an electronic dial); and various sorts of control information such as shutter speed or aperture value or the like are set according to the pulse signal from this electronic dial. Since with this sort of device the pulse signal from the electronic dial is transmitted electrically to a control device, in contrast with the mechanical type of dial in which the movement of some information setting operation member is transmitted mechanically via a cam or a linkage or the like, thereby the position of the electronic dial can be chosen with great freedom. Further, because the amount of force necessary to operate such an electronic dial is small, it is possible for the system to present a light and easy operational feel to the user. On the other hand, since the force required for the operation is so small, even brushing of the clothes or the like of the user against the electronic dial may cause it to be rotated, and therefore, if the user does not exercise sufficient care, there is a possibility that the setting state for the information may be inadvertently altered.
To overcome this problem, as disclosed for example in U.S. Pat. No. 5,291,236, there has been proposed the addition of an operation inhibition lock switch to such an electronic dial, with this lock switch being switchable between valid and invalid positions, so as respectively to enable or disable the information setting operation of the electronic dial. When such a lock switch is turned to its invalid position, the setting state of the information is not altered even if the electronic dial is moved. FIG. 13 shows an example of this type of prior art. In this figure the reference numeral 51 denotes the electronic dial, while 52 is a lock switch member. When the lock switch member 52 is shifted to its position denoted by "L", the input of information via the electronic dial 51 is prevented by electrical means, not particularly shown. Hereinafter in this specification, the state in which control information cannot be altered even though an information setting operation member such as the electronic dial described above is operated will be termed invalid state, while the state in which control information can be altered will be termed valid state.
When various types of control information are to be set for the camera by the use of such devices as described above, it is desirable for a separate electronic dial to be provided for each of the items of control information which need to be frequently changed, such as shutter speed and aperture value. However, if several electronic dials are provided, the provision of a lock switch of the type described above for each of these several electronic dials means that the number of control members is undesirably increased, and it becomes difficult to keep the design of the camera compact. Further if, from the situation in which all of the electronic dials are in their invalid states, all at once it becomes necessary immediately to put all of these dials into their valid states in order to establish a group of new control settings, it is necessary for the user to operate all of the plurality of lock switches in rapid succession, which is complex and troublesome.